The long-term objective of this project is to develop a cellular psychopharmacological monitoring system for freely behaving rodents, including rat models of brain disorders and transgenic mice. By developing new devices and procedures, cellular electrophysiological, behavioral and microdialysis techniques will be fused into a single, computer-controlled apparatus. In Phase I, a microprocessor-controlled, miniature liquid switch - dialysate collector/transporter, briefly called as minivalve, will be developed. This device will be placed on the head of the experimental animal, and will be connected to an intracerebrally implanted microdialysis probe/microelectrode unit. The minivalve will direct, through the microdialysis probe, either control or drug solution into the extracellular environment of the recorded neurons. Due to the closeness of the device to the neurons, the drug-induced cellular effects can be recorded within a minute. Furthermore, the minivalve will collect the dialysates, as they leave the brain, into a microreservoir, and fast-transport the collected fluid into the neurochemical analysis system. These novel features will open up a completely new way for determining cellular electrophysiological and neurochemical drug effects in the intact brain, during both normal and abnormal behaviors. The proposed minivalve will help to obtain new insights into the cellular electrophysiological and neurochemical basis of brain disorders, and can contribute to the discovery of new drugs for the treatment of these diseases. PROPOSED COMMERCIAL APPLICATION The proposed multifunctional minivalve will offer new opportunities in psychopharmacological research. Therefore, it is anticipated that the device will be popular among neuro- and psychopharmacologists in the academia. Since the minivalve will be a new tool for determining drug effects in brain, it is also anticipated that the device will also be widely used in in vivo laboratories in the pharmaceutical industry.